Effect Of Peptide Chain Length Research Articles

Microneedle enhanced delivery of cosmeceutically relevant peptides in human skin.

Peptides and proteins play an important role in skin health and well-being. They are also found to contribute to skin aging and melanogenesis. Microneedles have been shown to substantially enhance skin penetration and may offer an effective means of peptide delivery enhancement. The aim of this investigation was to assess the influence of microneedles on the skin penetration of peptides using fluorescence imaging to determine skin distribution. In particular the effect of peptide chain length (3, 4, 5 amino acid chain length) on passive and MN facilitated skin penetration was investigated. Confocal laser scanning microscopy was used to image fluorescence intensity and the area of penetration of fluorescently tagged peptides. Penetration studies were conducted on excised full thickness human skin in Franz type diffusion cells for 1 and 24 hours. A 2 to 22 fold signal improvement in microneedle enhanced delivery of melanostatin, rigin and pal-KTTKS was observed. To our knowledge this is the first description of microneedle enhanced skin permeation studies on these peptides.

ChemInform Abstract: The Influence of Secondary Structure on Electron Transfer in Peptides

AbstractReview: 22 refs.

The Influence of Secondary Structure on Electron Transfer in Peptides

A series of synthetic peptides containing 0–5 α-aminoisobutyric acid (Aib) residues and a C-terminal redox-active ferrocene was synthesised and their conformations defined by NMR and circular dichroism. Each peptide was separately attached to an electrode for subsequent electrochemical analysis in order to investigate the effect of peptide chain length (distance dependence) and secondary structure on the mechanism of intramolecular electron transfer. While the shorter peptides (0–2 residues) do not adopt a well defined secondary structure, the longer peptides (3–5 residues) adopt a helical conformation, with associated intramolecular hydrogen bonding. The electrochemical results on these peptides clearly revealed a transition in the mechanism of intramolecular electron transfer on transitioning from the ill-defined shorter peptides to the longer helical peptides. The helical structures undergo electron transfer via a hopping mechanism, while the shorter ill-defined structures proceeded via an electron superexchange mechanism. Computational studies on two β-peptides PCB-(β3Val-β3Ala-β3Leu)n–NHC(CH3)2OOtBu (n = 1 and 2; PCB = p-cyanobenzamide) were consistent with these observations, where the n = 2 peptide adopts a helical conformation and the n = 1 peptide an ill-defined structure. These combined studies suggest that the mechanism of electron transfer is defined by the extent of secondary structure, rather than merely chain length as is commonly accepted.

Peptide-intercalated layered metal hydroxides: effect of peptide chain length and side chain functionality on structural, optical and magnetic properties

New hybrid materials have been prepared by grafting synthetic peptides in the interlayer spacing of Cu(II) and Co(II) layered simple hydroxides (LSHs). The interlayer spacing of the hybrids depends on the peptide chain length; the dependence is specific for the copper and cobalt-based hybrids. This suggests a metal- or LSH-specific interaction of the peptides with the respective inorganic layers. When tyrosine is present in the peptide, its fluorescence is quenched after grafting the peptide to the LSH. Studies of the luminescence vs. pH indicate deprotonation of the tyrosine moieties to tyrosinate at high pH, accompanied by the onset of luminescence. The luminescence increases with increasing OH− concentration, suggesting an application of the hybrids as chemical sensors. Moreover, the peptides influence the magnetic properties of the hybrids. The copper-based hybrids behave antiferromagnetically and the cobalt-based hybrids are ferrimagnets.

Stabilization of Calcium Oxalate Metastable Phases by Oligo(l-glutamic acid): Effect of Peptide Chain Length

The understanding of the crystal growth of calcium oxalate and its inhibition is of great importance not only in medicine and biomineralization, but also in industry, as undesired deposits of this ...

Effects of chain length on oligopeptide hydrogelation.

The co-assembly of mutually complementary, but self-repulsive oligopeptide pairs into viscoelastic hydrogels has been studied. Oligopeptides of 6, 10, and 14 amino acid residues were used to investigate the effects of peptide chain length on the structural and mechanical properties of the resulting hydrogels. Biophysical characterizations, including dynamic rheometry, small-angle X-ray scattering (SAXS) and fluorescence spectroscopy, were used to investigate hydrogelation at the bulk, fiber, and molecular levels, respectively. Upon mixing, the 10-mer peptides and the 14-mer peptides both form hydrogels while the 6-mer peptides do not. SAXS studies point to morphological similarity of the cross-sections of fibers underlying the 10:10 and 14:14 gels. However, fluorescence spectroscopy data suggest tighter packing of the amino acid side chains in the 10:10 fibers. Consistent with this tighter packing, dynamic rheometry data show that the 10:10 gel has much higher elastic modulus than the 14:14 mer (18 kPa vs. 0.1 kPa). Therefore, from the standpoint of mechanical strength, the optimum peptide chain length for this class of oligopeptide-based hydrogels is around 10 amino acid residues.

Effect of Peptide Fragment Size on the Propensity of Cyclization in Collision-Induced Dissociation: Oligoglycine b2−b8

The chemistry of peptide fragmentation by collision-induced dissociation (CID) is currently being reviewed, as a result of observations that the amino acid sequence of peptide fragments can change upon activation. This rearrangement mechanism is thought to be due to a head-to-tail cyclization reaction, where the N-terminal and C-terminal part of the fragment are fused into a macrocycle (= cyclic peptide) structure, thus "losing" the memory of the original sequence. We present a comprehensive study for a series of b fragment ions, from b(2) to b(8), based on the simplest amino acid residue glycine, to investigate the effect of peptide chain length on the appearance of macrocycle fragment structures. The CID product ions are structurally characterized with a range of gas-phase techniques, including isotope labeling, infrared photodissociation spectroscopy, gas-phase hydrogen/deuterium exchange (using CH(3)OD), and computational structure approaches. The combined insights from these results yield compelling evidence that smaller b(n) fragments (n = 2, 3) exclusively adopt oxazolone-type structures, whereas a mixture of oxazolone and macrocycle b fragment structures are formed for midsized b(n) fragments, where n = 4-7. As each of these chemical structures exchanges at different rates, it is possible to approximate the relative abundances using kinetic fits to the H/D exchange data. Under the conditions used here, the "slow"-exchanging macrocycle structure represents approximately 30% of the b ion population for b(6)-b(7), while the "fast"-exchanging oxazolone structure represents the remainder (70%). Intriguingly, for b(8) only the macrocycle structure is identified, which is also consistent with the "slow" kinetic rate in the HDX results. In a control experiment, a protonated cyclic peptide with 6 amino acid residues, cyclo(Gln-Trp-Phe-Gly-Leu-Met), is confirmed not to adopt an oxazolone structure, even upon collisional activation. These results demonstrate that in some cases larger macrocycle structures are surprisingly stable. While more studies are required to establish the general propensity for cyclization in b fragments, the implications from this study are troubling in terms of faulty sequence identification.

Charge-Separation Reactions of Doubly-Protonated Peptides: Effect of Peptide Chain Length

The collision induced dissociation of doubly-protonated (Ala)(x)His (x = 5, 6, 7, 8, 10) peptides have been studied. The major fragmentation reactions observed are symmetrical amide bond cleavages to give the complementary b(m) and y(N-m) ions, where N is the total number of residues in the peptide. Minor asymmetric cleavage to give doubly-protonated y ions also is observed, involving cleavage near the N-terminus. The shorter peptides (x = 5, 6, 7) show major cleavage of the second amide bond to yield b2 and y(N-2) ions, while (Ala)10His shows major symmetrical cleavage at the fourth and fifth amide bonds. (Ala)8His appears to be a transitional peptide in showing substantial symmetrical cleavage at the second, fourth, and fifth amide bonds. The results are in general agreement with the bifurcating nature of charge separation noted by Zubarev (J. Am. Soc. Mass Spectrom.2008, 19, 1755-1763) from a statistical analysis of a large body of doubly-protonated tryptic peptide CID mass spectra. It is shown that the b2 ion derived from doubly-protonated (Ala)5His has a protonated oxazolone structure.

Effects of peptide chain length on the gas-phase proton transfer properties of doubly-protonated ions from bradykinin and its N-terminal fragment peptides

Proton transfer properties were studied for doubly-protonated ions from bradykinin and seven smaller peptides whose sequences have C-terminal residues successively removed from bradykinin. Ions were generated by electrospray ionization (ESI) and their deprotonation reactions were investigated in a Fourier transform ion cyclotron resonance mass spectrometer. Sustained off-resonance irradiation (SORI)-collision-induced dissociation (CID) was used to obtain information on sites of protonation, while molecular dynamics calculations provided information on peptide ion conformations and Coulomb energies. As the number of amino acid residues decreases the peptide ions undergo proton transfer more readily. Apparent gas-phase acidities (GA apps), for the doubly-protonated ions decreased as the peptide size decreased, with values spanning the range of 225.8±4.2 kcal/mol for the nonapeptide bradykinin to 196.6±4.4 kcal/mol for the tripeptide Arg 1Pro 2Pro 3. The magnitude of the drop in GA app as a residue was removed varied from 10.9 kcal/mol for removal of the highly basic Arg 9 to 0 kcal/mol for removal of Phe 8 (whose phenylalanine ring juts away from the peptide backbone and does not participate in hydrogen bonding). Hydrogen bonding in the modeled structures decreased as the peptide chain length decreased. The lowest energy structure for doubly-protonated bradykinin contained nine hydrogen bonds, while only one hydrogen bond was found for the tripeptide ions. In addition, the tripeptide ions had an extended structure, while the larger peptide ions were compact. There is no single reason that the peptide ions become more acidic (i.e., more reactive to proton transfer) as the peptide chain length is decreased. Depending upon the situation, factors that play a role in the proton transfer reactivity include intrinsic basicity of the protonation sites, intramolecular hydrogen bonding (particularly involving the protonated residue), Coulombic repulsion of charge sites, and conformational considerations such as accessibility/shielding of the protonation site.

The specificity of lysosomal tripeptidyl peptidase-I determined by its action on angiotensin-II analogues

Tripeptidyl peptidase-I (TPP-I) is a lysosomal peptidase which cleaves tripeptides from the N-terminus of peptides. The function of the enzyme is unclear but its importance is demonstrated by the fact that mutations in TPP-I are responsible for late infantile neuronal ceroid lipofuscinosis, a lethal lysosomal storage disease. As a step towards identifying its natural substrates, we have used a series of synthetic peptides, based on angiotensin-II, to explore the effects of peptide chain length and the effects of amino acid substitutions at the P 1 and P 1′ positions on the rate of catalysis. With the exception of angiotensin-(1–8) (angiotensin-II), which is a relatively poor substrate for TPP-I, the rate of catalysis increases with increasing chain length. K cat/ K m values increase 50-fold between angiotensin-(1–5) and angiotensin-(1–14). TPP-I shows little specificity for the nature of the amino acids in the P 1 and P 1′ positions, K cat/ K m values varying only 5-fold for a range of substitutions. However, Pro or Lys in the P 1 position and Pro in the P 1′ positions are incompatible with TPP-I activity. These observations suggest that TPP-I is a non-specific, but essential, peptidase involved in the latter stages of lysosomal protein degradation.

Small Peptide of Soybean Hydrolysate Is Absorbed More Rapidly than Large Peptide in the Perfused Rat Small Intestine.

The effects of peptide chain length on the absorption of soybean hydrolysates by the rat small intestine were investigated by the perfusion. Two types of soybean hydrolysates, a small peptide (SP; average peptide chain length: 3.2) and a large peptide (LP; average peptide chain length: 5.2), were prepared for this experiment. Krebs-Ringer phosphate buffer (pH 7.0) containing 0.5% (w/v) of either of the two types of soybean hydrolysates was perfused through a 15-cm length of rat jejunum for 70min. After the perfusion, samples were collected; and the total amount of amino acid was then measured by an amino acid analyzer (Hitachi L-8500) after hydrolysis. The absorption rate of each amino acid was subsequently determined. The absorption rate for glycine, alanine, isoleucine, leucine histidine, arginine, phenylalanine, and proline in SP was significantly greater than that for those in LP. The total amino acid absorption of SP was significantly greater than that of LP. There were no significant differences in the net absorption of water in the buffer solutions of SP and LP. We thus concluded that SP is more greatly absorbed than LP in the intestinal perfusion model of the rat small intestine.

Protonation of Glyn Homologues in Matrix-Assisted Laser Desorption Ionization

Protonation reactions of Glyn homologues were studied in order to elucidate the effect of peptide chain length and matrix materials on the matrix-assisted laser desorption ionization (MALDI) mechanism. At 337 nm nitrogen laser excitation the relative ion yield−chain length relationship showed considerable variability in 3,5-dimethoxy-4-hydroxycinnamic acid (SA), 2,5-dihydroxybenzoic acid (DHB), 6-aza-2-thiothymine (ATT), and α-cyano-4-hydroxycinnamic acid (CHCA), the four matrices studied. For SA and ATT, a monotonic increase of relative ion yields (RIYs) was observed with increasing peptide length. Similar increasing pattern and significantly higher RIYs were found for the homologues of the Glyn series in the CHCA matrix with the exception of Gly. The particularly high MALDI ion yield of this amino acid in CHCA may be attributed to preferential embedding and/or more efficient condensed-phase proton transfer. To unveil the nature of the proton-transfer reactions in MALDI, the peptide length dependence of the measured RIYs was compared to the trends observed in proton affinities (PAs) of the same homologues as well as to ion−molecule reaction rates calculated using the Langevin cross section. Chain extension enhancements in MALDI RIYs of all the studied matrices cannot be explained either by the increase in ground-state ion−molecule reaction rates or by a linear dependence on gas-phase PAs. However, in SA and ATT positive correlation was observed between MALDI RIYs of Glyn homologues and their PAs. The RIYs observed in CHCA were significantly higher than in SA. This effect could be explained by the markedly lower PA of CHCA (183 ± 2 kcal/mol) compared to that of SA (204 ± 4 kcal/mol).

Effect of Peptide Chain Length on Absorption and Intact Transport of Hydrolyzed Soybean Peptide in Rat Intestinal Everted Sac.

In this study using everted sacs of rat jejunum, we investigated the difference in absorption of two types of soybean peptides (small peptide: SP, and large peptide: LP). We investigated the influence of peptide length on absorption and intact transport of hydrolyzed soybean peptides. The everted sacs were incubated for 5 or 10 min in bicarbonate-saline buffer containing a 1% (w/v) concentration of each soybean peptide. After the incubation, the amounts of free amino acids and peptides that were transported to the serosal fluids and the mucosa were measured with an automatic amino acid analyzer both before and after the hydrolysis of the serosal fluids and mucosa. The results indicated that SP was absorbed more rapidly than LP and that the more rapid absorption of SP was due to the greater intact transport of SP. When the everted sacs were made from jejunum that had been injured by intraperitoneal injection of cyclophosphamide (300 mg/kg), no significant differences were noted between the absorption of SP and that of LP. We also ascertained that an aminopeptidase inhibitor (bestatin) decreased the aminopeptidase activities of the rat jejunum. In the presence of 1 x 10 -4 M bestatin in the incubation buffer, no significant differences were noted between the absorption of SP and that of LP. We conclude that SP is absorbed more rapidly than LP in normal rat jejunum due to greater intact transport.

Effect of chain length on the formation and stability of synthetic alpha-helical coiled coils.

A series of polypeptides containing 9, 12, 16, 19, 23, 26, 30, 33, and 35 amino acid residues was designed to investigate the effects of peptide chain length on the formation and stability of two-stranded alpha-helical dimers or coiled coils. These peptides were synthesized by the solid-phase method, purified by reversed-phase high-performance liquid chromatography (RP-HPLC), and characterized by RP-HPLC, amino acid composition analysis, and mass spectrometry. The amphipathic alpha-helical peptides were designed to dimerize by interchain hydrophobic interactions at positions a and d and interchain salt bridges between lysine and glutamic acid residues at positions e and g of the repeating heptad sequence of Glu-Ile-Glu-Ala-Leu-Lys-Ala (g-a-b-c-d-e-f). The ability of these peptides to form alpha-helical structures in the presence and absence of a helix-inducing reagent (trifluoroethanol) was monitored by circular dichroism spectroscopy. The helicity of the peptides increased with increasing chain length in a cooperative manner. A minimum of three heptads corresponding to six helical turns was required for a peptide to adopt the two-stranded alpha-helical coiled coil conformation in aqueous medium. The increased stability of the peptides as a result of an increase in hydrophobic interactions (chain length) was demonstrated by the shift in the transitions of the guanidine hydrochloride (Gdn.HCl) denaturation and thermal unfolding profiles. The concentrations of denaturant (Gdn.HCl) required to achieve 50% denaturation are 3.2, 4.9, 6.9, and 7.5 M for peptides 23r, 26r, 30r, and 33r, respectively, in aqueous medium. However, the effect of a chain length increase on coiled-coil stability was not additive. The melting temperature, Tm, at which 50% of the helicity is lost, increased by 34 degrees C in changing the peptide chain length from 23 to 26; however, that shift was only 14 degrees C when the chain length was increased from 30 to 33 residues. These results are consistent with a chain length dependent cooperative folding of the peptides into coiled coils.

Effect of peptide chain length on peptide retention behaviour in reversed-phase chromatogrphy

The use of amino acid retention or hydrophobicity coefficients for the prediction of peptide retention time and/or the elution order on hydrophobic stationary phases is based on the premise that amino acid composition is the major factor affecting peptide retention in reversed-phase chromatography. Although this assumption generally agrees well for small peptides (up to ca. 15 residues), the retention times of increasingly larger peptides are less than expected from a simple summation of retention coefficients. In the present study, we report the synthesis of four series of peptide polymers which vary significantly in overall hydrophobicity and polypeptide chain length (5–50 amino acid residues, Ac = acetyl): Ac-(G-L-G-A-K-G-A-G-V-G) n -amide ( n = 1–5), Ac-(G-K-G-L-G) n- amide ( n = 1,2,4,6,8, 10), Ac-(L-G-L-K-A) n -amide (n = l, 2, 4, 6, 8, 10) and Ac-(L-G-L-K-L) n -amide ( n = 1, 2, 4). From the retention behaviour of these peptide polymers on C 4, C 8 and C 18 stationary phases under gradient elution conditions, we have clearly established the effect of polypeptide chain length and hydrophobicity on peptide retention. This, in turn, has enabled us to extend the utility of retention time prediction for peptides containing up to 50 residues by introducing a peptide chain-length correction.

Effect of peptide chain length on absorption of egg protein hydrolysates in the normal human jejunum

The influence of the peptide chain length of partial enzymic hydrolysates of protein on nitrogen and amino acid adsorption was studied in 12 subjects using a jejunal perfusion technique. Three hydrolysates of egg white and an equivalent amino acid mixture were perfused at 30 mmol/L and 100 mmol/L in two separate experiments. Two hydrolysates (OH1 and OH2) contained mainly dipeptides and tripeptides, whereas the third (OH3) comprised tripeptide to pentapeptides as judged chromatographically. Nitrogen absorption was significantly slower from the higher chain length mixture, OH3, than from the short chain mixtures, OH1 and OH2, at both concentrations. Similarly, several amino acid residues were absorbed less well from OH3 than from OH1 and OH2. These data demonstrate that the chain length of heterogenous mixtures of peptides affects absorption of nitrogen and individual amino acid residues, and suggest that brush border hydrolysis of tetrapeptides and pentapeptides limits absorption from enzymic hydrolysates of protein which simulate the composition of the postprandial luminal contents.

Effect of peptide chain length on amino acid and nitrogen absorption from two lactalbumin hydrolysates in the normal human jejunum.

A double lumen jejunal perfusion technique has been used in man to study the effect of peptide chain length on absorption of amino acid nitrogen from two partial enzymic hydrolysates of lactalbumin. Copper-chelation chromatography showed that one lactalbumin hydrolysate (LH2) contained 98% peptides with a chain length greater than 4, whilst the other (LH1) contained a more even spread of chain lengths with 55% less than 4. Absorption of total nitrogen and of 14 amino acid residues occurred to a significantly greater extent from the low molecular weight LH1 than from the higher molecular weight LH2. The results suggest that the pattern of nitrogen and amino acid absorption from partial enzymic hydrolysates of whole protein is markedly influenced by peptide chain length and that brush border peptide hydrolysis has an important rate limiting effect on absorption rates.

The peptide nitrogen source of elemental diets — Effects of peptide chain length on absorptive characteristics : [formula omitted] Central Middlesex Hosp. Dept. of Gast. & Nutr., London, UK

The peptide nitrogen source of elemental diets — Effects of peptide chain length on absorptive characteristics : [formula omitted] Central Middlesex Hosp. Dept. of Gast. & Nutr., London, UK

Synthetic substrates for thyroid oligosaccharide transferase. Effects of peptide chain length and modifications in the Asn-Xaa-Thr-region.

The N-glycosylation of proteins is initiated by transfer of preassembled oligosaccharides from lipid carriers to an asparagine residue in the sequence Asn-Xaa-Ser(Thr). Various synthetic peptides were previously shown to act as effective acceptors when supplied to microsomal membranes. The present work was undertaken to delineate further within such peptides the structural determinants required for the N-glycosylation process. Several new peptides were synthesized to evaluate the effects of the chain length and of the modification on the asparagine, Xaa or threonine residues: asparagine was replaced by glutamine, Xaa by proline or N-methylated alanine, threonine by an homoserine residue. Furthermore, both side chains of asparagine and threonine were simultaneously replaced by those of glutamine and homoserine respectively to restore a putative hydrogen bonding between the carbonyl and hydroxyl groups. The assays were performed with a solubilized form of the oligosaccharide transferase and the acceptor capacities of the peptides expressed by the ratio V/Km of their apparent kinetic parameters V and Km. Results showed that N-acetyl-tripeptide amides are excellent substrates for the enzyme. All modifications in the -Asn-Xaa-Thr- region resulted in a loss of acceptor capacity. The importance of the conformational aspect is discussed.